Santanu Sarkar
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View article: A note on the analysis of Herrmann–May lattices for small exponent RSA
A note on the analysis of Herrmann–May lattices for small exponent RSA Open
At PKC 2010, Herrmann and May introduced a lattice-based method using unravelled linearization to achieve the theoretical bound for small RSA exponents. In this paper, we identify an error in their asymptotic analysis, revising…
View article: Significantly Improved Cryptanalysis of Salsa20 with Two-Round Criteria
Significantly Improved Cryptanalysis of Salsa20 with Two-Round Criteria Open
Over the past decade and a half, cryptanalytic techniques for Salsa20 have been increasingly refined, largely following the overarching concept of Probabilistically Neutral Bits (PNBs) by Aumasson et al. (FSE 2008). In this paper, we prese…
View article: New Quantum Cryptanalysis of Binary Elliptic Curves
New Quantum Cryptanalysis of Binary Elliptic Curves Open
This paper improves upon the quantum circuits required for the Shor’s attack on binary elliptic curves. We present two types of quantum point addition, taking both qubit count and circuit depth into consideration.In summary, we propose an …
View article: J-contractive operator valued functions, vector valued de Branges spaces and functional models
J-contractive operator valued functions, vector valued de Branges spaces and functional models Open
The aim of this paper is to study the vector valued de Branges spaces, which are based on $J$-contractive operator valued analytic functions, and to explore their role in the functional models for simple, closed, densely defined, symmetric…
View article: Implementing Grover’s on AES-based AEAD schemes
Implementing Grover’s on AES-based AEAD schemes Open
Extensive research is currently underway to determine the security of existing ciphers in light of the advancements in quantum computing. Against symmetric key cryptography, Grover’s search algorithm is a prominent attack, capable of reduc…
View article: de Branges matrices and associated de Branges spaces of vector valued entire functions
de Branges matrices and associated de Branges spaces of vector valued entire functions Open
This paper extends the concept of de Branges matrices to any finite $m\times m$ order where $m=2n$. We shall discuss these matrices along with the theory of de Branges spaces of $\mathbb{C}^n$-valued entire functions and their associated f…
View article: Algebraic Attack on FHE-Friendly Cipher HERA Using Multiple Collisions
Algebraic Attack on FHE-Friendly Cipher HERA Using Multiple Collisions Open
Fully homomorphic encryption (FHE) is an advanced cryptography technique to allow computations (i.e., addition and multiplication) over encrypted data. After years of effort, the performance of FHE has been significantly improved and it ha…
View article: Enhancing the Key Recovery Attack on Round Reduced Salsa
Enhancing the Key Recovery Attack on Round Reduced Salsa Open
Salsa is the most well-known stream cipher and a finalist of the eSTREAM project. The concept of probabilistic neutral bits (PNBs) first presented by Aumasson et al., is the most important step in the cryptanalysis of Salsa. In this paper,…
View article: Revisiting Yoyo Tricks on AES
Revisiting Yoyo Tricks on AES Open
At Asiacrypt 2017, Rønjom et al. presented key-independent distinguishers for different numbers of rounds of AES, ranging from 3 to 6 rounds, in their work titled “Yoyo Tricks with AES”. The reported data complexities for these distinguish…
View article: Representing the inverse map as a composition of quadratics in a finite field of characteristic $2$
Representing the inverse map as a composition of quadratics in a finite field of characteristic $2$ Open
In 1953, Carlitz~\cite{Car53} showed that all permutation polynomials over $\F_q$, where $q>2$ is a power of a prime, are generated by the special permutation polynomials $x^{q-2}$ (the inversion) and $ ax+b$ (affine functions, where $0\ne…
View article: A new distinguishing attack on reduced round ChaCha permutation
A new distinguishing attack on reduced round ChaCha permutation Open
This work concentrates on differential-linear distinguishing attacks on the prominent ARX-based permutation ChaCha. Here, we significantly improve the 7-round differential-linear distinguisher for ChaCha permutation by introducing a new pa…
View article: Spread and asymmetry of typical quantum coherence and their inhibition in response to glassy disorder
Spread and asymmetry of typical quantum coherence and their inhibition in response to glassy disorder Open
We consider the average quantum coherences of typical redits and qudits—vectors of real and complex Hilbert spaces—with the analytical forms stemming from the symmetry of Haar-uniformly distributed random pure states. We subsequently study…
View article: Some aspects of vector valued de Branges spaces of entire functions
Some aspects of vector valued de Branges spaces of entire functions Open
This paper deals with certain aspects of the vector valued de Branges spaces of entire functions that are based on pairs of Fredholm operator valued functions. Some factorization and isometric embedding results are extended from the scalar…
View article: Vector valued de Branges spaces of entire functions based on pairs of Fredholm operator valued functions and functional model
Vector valued de Branges spaces of entire functions based on pairs of Fredholm operator valued functions and functional model Open
In this paper, we have considered vector valued reproducing kernel Hilbert spaces (RKHS) $\mathcal{H}$ of entire functions associated with operator valued kernel functions. de Branges operators $\mathfrak{E}=(E_- , E_+)$ analogous to de Br…
View article: Uncertainty principle for Weyl transform and Fourier–Wigner transform
Uncertainty principle for Weyl transform and Fourier–Wigner transform Open
We prove an uncertainty type principle for finite linear combinations of Fourier--Wigner transforms. This is equivalent to proving a finite rank theorem for the Weyl transform.
View article: New Low-Memory Algebraic Attacks on LowMC in the Picnic Setting
New Low-Memory Algebraic Attacks on LowMC in the Picnic Setting Open
The security of the post-quantum signature scheme Picnic is highly related to the difficulty of recovering the secret key of LowMC from a single plaintext-ciphertext pair. Since Picnic is one of the alternate third-round candidates in NIST…
View article: New Cryptanalysis of ZUC-256 Initialization Using Modular Differences
New Cryptanalysis of ZUC-256 Initialization Using Modular Differences Open
ZUC-256 is a stream cipher designed for 5G applications by the ZUC team. Together with AES-256 and SNOW-V, it is currently being under evaluation for standardized algorithms in 5G mobile telecommunications by Security Algorithms Group of E…
View article: Differential faultt attack on DEFAULT
Differential faultt attack on DEFAULT Open
Block cipher DEFAULT has been proposed as a differential fault analysis immune cipher at Asiacrypt 2021. In this paper, we consider the initial version of DEFAULT with no permutation involved in the last round and show that one can find th…
View article: Weak-keys and key-recovery attack for TinyJAMBU
Weak-keys and key-recovery attack for TinyJAMBU Open
In this paper, we study NIST lightweight 3 rd round candidate TinyJAMBU. The core component of TinyJAMBU is the keyed permutation P n , which which is based on a non-linear feedback shift register. By analysing this permutation carefully, …
View article: Spread and asymmetry of typical quantum coherence and their inhibition in response to glassy disorder
Spread and asymmetry of typical quantum coherence and their inhibition in response to glassy disorder Open
We consider the average quantum coherences of typical redits and qudits - vectors of real and complex Hilbert spaces - with the analytical forms stemming from the symmetry of Haar-uniformly distributed random pure states. We subsequently s…
View article: Side Channel Attack On Stream Ciphers: A Three-Step Approach To State/Key Recovery
Side Channel Attack On Stream Ciphers: A Three-Step Approach To State/Key Recovery Open
Side Channel Attack (SCA) exploits the physical information leakage (such as electromagnetic emanation) from a device that performs some cryptographic operation and poses a serious threat in the present IoT era. In the last couple of decad…
View article: Diving Deep into the Weak Keys of Round Reduced Ascon
Diving Deep into the Weak Keys of Round Reduced Ascon Open
At ToSC 2021, Rohit et al. presented the first distinguishing and key recovery attacks on 7 rounds Ascon without violating the designer’s security claims of nonce-respecting setting and data limit of 264 blocks per key. So far, these are t…
View article: Atom: A Stream Cipher with Double Key Filter
Atom: A Stream Cipher with Double Key Filter Open
It has been common knowledge that for a stream cipher to be secure against generic TMD tradeoff attacks, the size of its internal state in bits needs to be at least twice the size of the length of its secret key. In FSE 2015, Armknecht and…
View article: Differential fault location identification by machine learning
Differential fault location identification by machine learning Open
As the fault‐based attacks are becoming a more pertinent threat in today's era of edge computing/internet‐of‐things, there is a need to streamline the existing tools for better accuracy and ease of use, so that we can gauge the attacker's …
View article: A Hybrid Inversive Congruential Pseudorandom Number Generator with High Period
A Hybrid Inversive Congruential Pseudorandom Number Generator with High Period Open
Though generating a sequence of pseudorandom numbers by linear methods (Lehmer generator) displays acceptable behavior under some conditions of the parameters, it also has undesirable features, which makes the sequence unusable for variou…
View article: Some results on lightweight stream ciphers Fountain v1 & Lizard
Some results on lightweight stream ciphers Fountain v1 & Lizard Open
In this paper, we propose cryptanalytic results on two lightweight stream ciphers: Fountain v1 and Lizard. The main results of this paper are the followings:$ - $ We propose a zero-sum distinguisher on reduced round Fountain v1. In this co…